'97 F Super Duty Trailer Wiring

[JJZ 109]

Anyone know where to find a diagram of the factory box mounted on the rearmost frame crossmember?
The guy who sold me the truck cobbled in a 7 pin connector and trailer brake controller for me. The brake controller has wires run from it to the rear of the trailer by hand instead of plugging into the under dash connector. I plan on getting a new controller and fixing that.
Also would like to get a new piece of trailer whip and tie the lighting and brake wires from that factory box to a new 7 pin connector. The box is clean as a whistle inside.

 

[Diamondpilot]

Never seen one but maybe try your Ford dealer. If they can not help get out the test light and a pad and pen.

Chris

 

[JJZ 109]

Never seen one but maybe try your Ford dealer. If they can not help get out the test light and a pad and pen.

Chris

It's a nice rectangular box tucked up inside a crossmember. Looks like there's power coming in from the truck and then out to a 4 pin connector and more wires out to a 7 pin. 3 glass fuses in there also. I'm assuming for power in and the 2 power outs.
Today I bought a new trailer brake controller and the little whip to plug it into the stock plug under dash. That should eliminate some of the confusion for me.
Update:
No luck getting trailer brakes. Bought a new controller and whip at Auto Zone. Plugged it into the under dash factory plug. Power to the controller, the LED display works when any buttons are pushed. Can't seem to find anything at the rear of the truck to power the trailer brakes. Looks like it's off to someone with more expertise and patience than me.

 

[JJZ 109]

The truck plug is wired according to the diagram shown.
That caused some goofy things with the trailer. Apparently the brown on the trailer wiring is not parking/tail lamps. Brown on the trailer is right turn. I think green on the trailer is tail lamps.
At any rate, a couple of switched wires on the trailer plug and we have lights. Got to get those brakes going though.

 

[Diamondpilot]

Hmmm, wonder why someone screwed around with the trailer?:confused2: At any rate keep the truck to industry standards so you will not have issues with other trailers.

Chris

 

[JJZ 109]

At any rate keep the truck to industry standards so you will not have issues with other trailers.

Chris

That was my plan when I downloaded that diagram. Keep the truck to the standard because I have another 7 pin trailer.
Fortunately nobody else pulls the enclosed trailer for me.

 

[tcartwri]

There's obviously a reason for the factory harness to have been bypassed. I would keep that in the back of your mind while you are diagnosing.

Is there a breakaway switch and battery on the trailer for the brakes?

 

[some zilch]

i just bought a '97 f-super duty and wired for a trailer as well. there was no factory plug for a BC in mine, nor was there any black box in the rear of the truck. my truck was clearly never equipped to tow, and it most likely never had (no hitch, or provisions for even a bumper ball). i had no issues wiring in a BC, and running my own wires for it, and just tapped off the rear truck lights for the trailer's lights. i think there was a TON of variation in trucks of that era and tons of different option/commercial packages. who knows what a previous owner hacked in or out. sometimes its just easier to start fresh

 

[Diamondpilot]

i just bought a '97 f-super duty and wired for a trailer as well. there was no factory plug for a BC in mine, nor was there any black box in the rear of the truck. my truck was clearly never equipped to tow, and it most likely never had (no hitch, or provisions for even a bumper ball). i had no issues wiring in a BC, and running my own wires for it, and just tapped off the rear truck lights for the trailer's lights. i think there was a TON of variation in trucks of that era and tons of different option/commercial packages. who knows what a previous owner hacked in or out. sometimes its just easier to start fresh

If you are towing with a non tow equipped truck I would add a large or larger tranny cooler asap. You can get one for under $100 and it will save you tons in the long run.

Chris

 

[JJZ 109]

There's obviously a reason for the factory harness to have been bypassed. I would keep that in the back of your mind while you are diagnosing.

Is there a breakaway switch and battery on the trailer for the brakes?

Yup, breakaway switch & battery on trailer.
As far as the truck, in another life it was a Bell Atlantic truck. I've found all sorts of clipped wires for stuff that is no longer part of the truck. However, all equipment currently with the truck works with the exception of finding whatever wire comes from the factory harness for the trailer brakes.
The box at rear of frame that was mentioned earlier is where the truck's 7 pin plug is wired from. I've got all lights functioning out of it. As I said, kind of a neat setup. There are three fuses in it.